1. Field of the Invention
The present invention relates to a droplet ejection head and a method of manufacturing a droplet ejection head, and more particularly to a droplet ejection head and a method of manufacturing a droplet ejection head in which liquid repelling properties are imparted to a droplet ejection surface.
2. Description of the Related Art
In a droplet ejection head used in an image forming apparatus, or the like, when droplets have adhered to the surface of a nozzle plate, the adhering droplets affect droplets succeedingly ejected from the nozzles, and thereby variation may occur in the ejection directions of the succeeding droplets. It is then difficult to deposit the ejected droplets at prescribed positions on a recording medium and this causes deterioration of image quality. In order to prevent droplets from adhering to the surface of the nozzle plate, various methods for imparting water repelling properties to the surface of the nozzle plate have been proposed.
For example, Japanese Patent Application Publication No. 2000-229410 discloses that a water repelling function is imparted by forming a protruding and recessing structure on a surface of a substrate. However, if an un-structured flat surface does not have water repelling properties, then even if the protruding and recessing structure is subsequently foamed on the surface, no water repellence enhancing effect occurs. Hence, in general, the surface that has the protruding and recessing structure is coated with a water repelling film (see Japanese Patent Application Publication Nos. 2000-226570 and 06-122204).
On the other hand, when droplets have adhered to the surface of the nozzle plate, it is necessary to remove the droplets by wiping, or the like. Consequently, the durability, such as wear resistance, of the surface of the nozzle plate has to be improved. Therefore, a protruding and recessing structure is formed by means of a diamond-like carbon (DLC) film or a hard resin film (see Japanese Patent Application Publication Nos. 2009-113351, 2009-107314 and 2009-066876).
However, the water repelling films described in Japanese Patent Application Publication Nos. 2000-226570 and 06-122204 are thin films made from fluorine-containing organic silicon compounds, and hence there is a problem in that durability, principally the wear resistance, is poor. Furthermore, in the droplet ejection heads described in Japanese Patent Application Publication Nos. 2009-113351, 2009-107314 and 2009-066876, the surface that has the protruding and recessing structure is coated with a water repelling material or the protruding and recessing structure is made of a water repelling resin such that the water repelling properties are exhibited. Consequently, the protruding and recessing structure can be formed of a material of high durability, but since the outermost surface is made of the organic water repelling material, then significant improvement in the durability of the water repelling film is not observed.